


Stepping up

by notallballs (notallbees)



Category: Haikyuu!!
Genre: Age Difference, Alpha Iwaizumi Hajime, Alpha/Beta/Omega Dynamics, Awkward Crush, Consensual Infidelity, Cunnilingus, First Time, Infidelity, Iwaizumi Chiaki, Knotting, Lactation, Loss of Virginity, M/M, Male Lactation, Massage, Mating Cycles/In Heat, Mpreg, Multiple Orgasms, Non-Traditional Alpha/Beta/Omega Dynamics, Omega Oikawa Tooru, Oral Sex, Polyamory, Pregnancy, Pregnant Sex, Wet & Messy
Language: English
Status: In-Progress
Published: 2019-04-05
Updated: 2019-04-13
Packaged: 2019-12-30 14:19:07
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 13,135
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18316976
Author URL: https://archiveofourown.org/users/notallbees/pseuds/notallballs
Summary: "Are you sure you don't mind babysitting, kiddo?" Hajime asked, reaching out to ruffle Chiaki's hair."Iwa-chan, don't call it babysitting!" Tooru complained from the doorway.Chiaki grinned. "I don't mind," he said, looking over at Tooru. Tooru was leaning against the door frame and holding his round belly again, and he grinned when he saw Chiaki looking his way."You can back out if you want to," Hajime said, frowning."Don't be silly, Iwa-chan," Tooru put in, flapping one hand dismissively. "We're going to have fun, aren't we, Chiaki-chan?"When Iwaizumi has to leave his heavily pregnant boyfriend behind for a work trip, his younger brother agrees to help out.But Chiaki soon finds himself in over his head as he starts to see Oikawa in a new light, and Oikawa's demands for attention go far beyond what he signed up for.





	1. Chapter 1

**Author's Note:**

> "hey bees what if you finished some of your wips"  
> "bees what about your commissions"  
> "yo bees how about writing ships people actually want to read" 
> 
> good points, all. here's this instead.
> 
>  
> 
>  **Warning:** see end note for my standard omegaverse warning. Also, this is a Chiaki/Oikawa fic. It's an iwaoi fic too, but please don't be surprised when Chiaki and Oikawa start getting nasty. I've made the tags as clear as I could.

Chiaki pulled out his phone as he walked up from the platform. Hajime had promised to meet him at the station, and sure enough, just as Chiaki stepped through the gate he heard the sound of his name over the crowd, and looked up to find Hajime waving at him. He grinned back, and made his way over there. 

"It's good to see you!" Hajime said, pulling him into an exuberant hug. "I missed you." 

Chiaki laughed and hugged him back. "Missed you too, nii-san," he said, beaming. "Is Tooru here as well?" 

Hajime shook his head. "With any luck he's resting, although I doubt it. Come on." He reached to take Chiaki's bag from him, and started to lead him out of the station.

"How's Tooru doing?" Chiaki asked.

"Fine," Hajime said, sighing. "You know what he's like, he can't sit still."

Chiaki grinned. "Sounds like someone else I know."

"Don't you start."

As they walked to Hajime and Tooru's apartment, they talked for a while about Tooru and the baby, and then about Chiaki's architecture course. It was almost six months since Chiaki had last seen his brother; there hardy ever seemed to be time for it now that he was at uni, and he'd missed him terribly. It felt a little unfair that they wouldn't see much of each other on this visit either, but Chiaki resolved to make up for it before the end of the summer.

When they were a few streets away, Hajime steered them off their path to visit the nearest convenience store, where he picked up two boxes of popsicles and a handful of other odds and ends. 

"Oikawa's got cravings," was the only explanation he offered, expression grim. 

The apartment was warm when they stepped inside, and Chiaki pulled at the front of his t-shirt to fan himself while he stepped out of his trainers. He hoped their air conditioning wasn't broken again, like it had been the last time he visited. 

Oikawa came to the end of the hallway as Chiaki stepped out of the genkan, holding his large, swollen belly with one hand. "Chiaki!" he said brightly, his face lighting up. 

Chiaki grinned at him. "Hi, Tooru." 

"You've grown," Tooru said, taking a few waddling steps toward him and holding his arms out. "Let me give you a hug." 

"Oikawa," Hajime growled. "It's too hot for that."

"I don't mind," Chiaki said, moving forward to wrap his arms around Tooru. 

Tooru was still taller than him, although Chiaki had finally almost caught him up. Chiaki wasn't sure at first how hard he ought to hold him, but Tooru winched him in tight without hesitation, pressing his hot cheek against the side of Chiaki's neck. His arms were strong and solid against Chiaki's back, and his swollen stomach pressed against him, strangely intimate despite the layers of clothing between them. 

The unexpected contact made a flush tear across Chiaki's face. He was used to Tooru being hands on, but this was a lot, even for him.

"Oi, give him some space, Tooru," Hajime grumbled. "And why'd you turn the air con off?" 

"I was cold," Tooru said in a sniffy voice as he pulled away. "But now that you two are home, you can warm me up!"

Hajime rolled his eyes, and started to herd Tooru in the direction of the living room. "You were too hot when I left. I brought you popsicles." 

"Iwa-chan!" Tooru cheered. "You _do_ love me."

"Don't be an idiot," Hajime growled, the back of neck reddening. 

The three of them moved into the other room together, and Hajime fetched barley tea and snacks as they talked, fulfilling Tooru's various requests. Chiaki couldn't help but take note of how much more solicitous Hajime was being than usual; normally he would've told Tooru where to stick it rather than run around after him, but now he was doing it without complaint. Tooru, almost eight months pregnant, was clearly revelling in it. Now that he was sitting, Chiaki could finally feel the effects of the air conditioning, and he sipped his cool tea happily in between answering Tooru's questions, and watching the two of them bicker. 

"Hajime," Tooru whined, when they'd been chatting for an hour or so. "Could I have another popsicle?"

"One's enough," Hajime said, giving him a severe look. 

Tooru pouted at him. "Chiakkun would get me another one. Wouldn't you, Chiakkun?"

Chiaki froze, his drink halfway to his mouth. "Uh—"

"Ignore him," Hajime said, rolling his eyes. Then, to Tooru. "Don't you dare boss him around while I'm gone. He's here to help out, not to be your servant."

"I don't mind," Chiaki ventured, but Hajime sent him a furious look.

"Yes you do," he said shortly. 

Chiaki smiled helplessly at Tooru. 

"Alright," Hajime sighed, a few minutes later. "Time for me to leave." 

"Do you need a hand with your bags?" Chiaki asked, getting to his feet.

Hajime shook his head. "I'll be fine. Tooru, you need anything before I go?"

"Nope," Tooru sighed, putting his hands on the edge of the table. He started to push himself up, then winced. "Chiakkun—"

"I've got it," Chiaki said, hurrying forward. He reached down to grasp Tooru's wrists, then pulled him to his feet. Tooru was even heavier than he expected, but it wasn't that surprising, given his height and build, not to mention the additional baby weight. 

Tooru grinned as he finally found his feet. "Thanks, Chiakkun," he said. "I just got a little stiff sitting there so long."

They made their way out into the hallway, where Hajime was just emerging from his and Tooru's bedroom with a small suitcase and a densely packed backpack. "Are you sure you don't mind babysitting, kiddo?" Hajime asked, reaching out to ruffle Chiaki's hair. 

"Iwa-chan, don't call it babysitting!" Tooru complained from the doorway. 

Chiaki grinned. "I don't mind," he said, looking over at Tooru. Tooru was leaning against the door frame and holding his round belly again, and he grinned when he saw Chiaki looking his way. 

"You can back out if you want to," Hajime said, frowning. 

"Don't be silly, Iwa-chan," Tooru put in, flapping one hand dismissively. "We're going to have fun, aren't we, Chiaki-chan?" 

Chiaki nodded. "It's okay, nii-san," he said, beaming at Hajime. "You don't need to worry about Tooru and the baby, I'll take good care of them." 

Hajime laughed. "I know you will." He put his hands on Chiaki's shoulders and looked at him for a moment before pulling him into a tight hug. "Thanks for this, kiddo," he sighed into Chiaki's shoulder. "I really owe you." 

"It's okay," Chiaki said again, laughing awkwardly. "I wanna help! Plus, your apartment has air conditioning." 

Hajime snorted as he pulled away. "Tooru would've strangled me by now if it didn't." 

"That's right," Tooru said proudly. "Come on now, Iwa-chan. You're going to miss your flight if you're not careful." 

"Yeah, yeah," Hajime sighed, taking a few steps over to Tooru. He reached out with both hands, and Chiaki glanced away as the two of them folded into an embrace. His brother had been close to Tooru ever since he could remember, and they'd been together almost as long, but he couldn't help but feel like a voyeur to be seeing them in such an intimate moment. Standing so close to them, every sigh and murmur was audible to him, from the sound of Hajime rubbing his cheek against Tooru's neck and inhaling him deeply, to the soft, longing sigh Tooru let out when Hajime drew back and kissed him.

"Come back soon," Tooru whispered, holding Hajime's face between his hands. "We'll miss you." 

Hajime nodded. "I'll miss you too." He took a step back, then bent down to kiss Tooru's stomach through his t-shirt. "Be good for Uncle Chiaki," he murmured to Tooru's bump. 

Chiaki looked up at the sound of his name, the back of his neck burning. 

"Let me know if Tooru gives you any trouble," Hajime said, and winked at him. "Don't let him push you around."

"I don't mind," Chiaki said, smiling, hoping Hajime wouldn't notice his hot cheeks. If he did, he didn't say anything, just gave them both a cheerful wave before heading out.

As soon as the door closed, Tooru cleared his throat. "Sorry for embarrassing you, Chiaki-chan." 

Chiaki swallowed. "That's okay. I—I mean, you didn't." 

"I'm glad to hear it," Tooru said. He turned back toward the living room. "Now, let's find something fun to do that Iwa-chan would disapprove of."

 

—

 

Taking care of Tooru wasn't too difficult. Chiaki was in the middle of his summer break, so there wasn't much for him to do besides using Hajime's gym pass, or catching up on some of his summer homework. He and Tooru went to the park the first morning after Hajime left for his business trip, where they spent a couple of hours walking around in the sunshine, before it grew too hot and they retired to the safety of a café to eat shaved ice. 

"Is there anything you want to do while you're here?" Tooru asked, reaching over to steal a spoonful of fruit from Chiaki's side of the bowl. "It's a while since you've visited Tokyo, right?"

Chiaki shrugged. "I dunno. I'm happy to do whatever."

Tooru grinned and used his spoon to point at him. "Iwa-chan was right, you know. You don't have to just go along with whatever I say."

"That's not—I mean, I really don't mind," Chiaki said earnestly. "I just want to make sure you're okay. Dad said it's really hard being pregnant."

"Ah, well," Tooru said, shrugging. "It has its ups and downs."

Chiaki bit his lip. "Does it hurt?"

Tooru laughed. "Which part?" he asked, grinning. "Some of it does. My boobs ache, especially now that I've started getting milk, and the hedgehog likes to kick."

"That hurts?" Chiaki asked, wide-eyed. He tried to ignore the part about Tooru's boobs, because if he let himself linger on that for more than a moment, he was going to start blushing. Tooru had always been lean and flat-chested, but his breasts had filled out over the last few months, and the strap of his bralette was visible where the neck of his t-shirt had slipped sideways. Growing up, Chiaki hadn't really noticed that Tooru was attractive. He was like a second older brother, just another of Hajime's friends. Chiaki wasn't sure if it was because he was older now, or just because they saw each other much less now—or, he thought, trying not to look too hard at the thought, was it something about Tooru being pregnant?—but now he couldn't seem to _un_ see it. Tooru's smile was bright and warm, his hair soft and shiny—longer than it used to be—and his body, well. Chiaki really enjoyed the sight of Tooru's newly soft figure, with curves where there didn't used to be. He swallowed down a pang of guilt and hurriedly pushed the thought aside. 

"It doesn't really hurt," Tooru said, shaking his head, snapping Chiaki back to reality. "It feels a little strange, that's all. But when she's got a knee or an elbow jabbing me in the bladder…" He paused, laughing. "Well, that's the least of my worries, but I won't terrify you with the rest, Chiakkun. Just be glad you're an alpha."

Chiaki nodded mutely. 

"What do you say we go to the planetarium later?" Tooru suggested. 

Chiaki brightened. "Are you sure?"

Tooru nodded. "As long as you don't mind me leaning on you if I get tired."

"Of course not!" Chiaki said, beaming. Truthfully, he rather liked the idea of Tooru relying on him a little bit. Chiaki was used to being the baby of the family, and even Takeru was an only child, even if Tooru was sort of like an older brother to him, so he was used to his mother trusting him with his own responsibility. For Chiaki, there had always been his parents, and Hajime. This was, he realised, the first time he'd ever really been left in charge of anything. "You can lean on me all you want, Tooru," he said brightly. "While I'm here, you can ask me to do anything."

"Careful, Chiakkun," Tooru said with a dangerous smile. "You might regret saying something like that."

 

—

 

Chiaki woke early the next morning, gasping for breath in the stifling cupboard that was the guest bedroom. The thin sheet was sticking to his skin, and his underwear was damp with sweat. He changed into a fresh pair and stumbled, still half asleep, out into the hallway. Tooru was already there, a thin cardigan draped loosely around his shoulders, swearing profusely as he fiddled with the control panel for the air con.

"Tooru?" Chiaki murmured, reaching up to stifle a yawn. 

"Shit," Tooru hissed, slamming the panel shut and yanking his cardigan closed. "Sorry, did I wake you, Chiakkun?"

Chiaki shook his head, only half listening. His eyes dropped of their own accord, taking in Oikawa's similar lack of attire. His long, slim legs were bare, and the lace edge of his underwear showed beneath the hem of his cardigan. He wasn't wearing anything underneath it. 

"Chiakkun?"

"Sorry!" Chiaki yelped, snapping his gaze up to Tooru's face. 

Tooru sighed. "I think it's broken. I'll try and call someone to come and fix it."

Chiaki nodded. "Want me to go buy some ice?"

"You're my hero, Chiakkun," Tooru sighed, turning away and waddling toward his bedroom. "I'll make us some breakfast in a minute."

Chiaki dressed hurriedly and jogged to the convenience store to pick up some ice and a few other sundries. Despite the early hour, it was already hot out, and he was sweating when he returned to the apartment, which was like an oven. Tooru was in the kitchen, his hair damp from showering, but he wasn't wearing much more than when Chiaki had left. His thin, oversized shirt already had a damp patch between his shoulders, and his long legs were still bare. Chiaki swallowed thickly and looked the other way. 

"I got a few bags of ice," he murmured, setting his shopping bag on the counter. 

"Thank you, Chiakkun!" Tooru said, beaming at him. He patted Chiaki's shoulder, and nudged him gently toward the living room. "Go set up the table, we can eat in a minute."

After they'd eaten, Tooru called a repair company, but from the way his tone became more pristine and saccharine as the conversation progressed, it clearly wasn't good news. 

"Bastards," he hissed after hanging up. "They said they can't send someone out for at least three days."

Chiaki winced. "Maybe someone else could do it?"

"Maybe," Tooru sighed, unconvinced.

"I'll call around," Chiaki promised. "Don't worry about it."

Tooru flashed him a weak smile. "Thanks, Chiakkun."

Chiaki made an attempt, but after ringing four different repair companies, the earliest anyone was available to come out was in two days' time. He thanked them for their trouble, and resigned himself to spending two days alone in the sweltering apartment with a half-dressed Tooru. When he went back to the living room to break the news, Tooru was leaning back against the couch, his legs spread out in front of him, and rolling an ice cube back and forth along his collarbone. As Chiaki watched, a bead of water rolled down Tooru's chest, and disappeared into the soft blue fabric of his bralette. Chiaki swallowed thickly, and cleared his throat.

Tooru brightened when he noticed Chiaki, but his shoulders slumped as Chiaki haltingly apologised about the repair disappointment. "Why now?" he moaned, slouching down further against the couch. "This is all Iwa-chan's fault," he added in a grumpy tone. "He was supposed to knock me up in August so I could be pregnant over the winter instead."

"What date is she due again?" Chiaki asked, hoping to distract him.

But Tooru only looked more mournful, dropping one wet hand to cradle his bare stomach. "September 19th," he said, sighing. "I can't wait."

"Maybe we should go to the mall," Chiaki suggested, without much enthusiasm. "At least it would be air-conditioned there."

"Oh! That's a great idea!" Tooru said, perking up again. 

Chiaki winced. "Although I guess we'd have to take the train to get there."

"Oh, yes," Tooru said, his face falling. "Still, I can't just not take a single train for the next six weeks." He sat up and clapped his hands together. "Come on, Chiakkun. Let's go out and do something fun."

"Okay," Chiaki said, a relieved smile crossing his face. If they were out in public, Tooru would have to have clothes on, and that meant Chiaki couldn't stare at him. It also meant he'd be able to breathe in without getting a lungful of Tooru's thick, comforting scent, which was only getting stronger the longer they sat there sweating. 

 

—

 

They spent the afternoon at the mall, and then stayed out for dinner, to avoid going back to the apartment until they had to. Tooru insisted on paying for Chiaki's meal despite his protests, and plied him with several beers, arguing that he couldn't drink and therefore Chiaki had to drink for two. By the time they made it home, Chiaki was still lightheaded and giggly, and he couldn't seem to stop his gaze from lingering when Tooru started stripping off in the hallway. 

"I swear I'm melting," Tooru groaned, peeling off his thin leggings and kicking them to one side of the hall. His shirt followed, until he stood in his underwear, running his fingers through the short, damp hairs at the back of his neck. "I shouldn't have walked so much."

"Do your feet hurt?" Chiaki asked, dragging his eyes up from Tooru's bare thighs and full, round backside. 

Tooru sighed. "Feet, ankles, calves. I'd go soak in the bath but I can't bear being hot anymore."

Chiaki's throat clenched, and he moved his mouth uselessly for a few moments before he managed to get any words out. "I could help. Give you a massage or something."

"You don't have to do that," Tooru murmured, not turning to look at him.

"I don't mind," Chiaki said, taking a step closer to him. "I want to help."

Tooru glanced back over his shoulder, holding Chiaki's gaze for a moment before turning away and walking into the living room. "If you're sure!" he called back. "There's some coconut oil in the kitchen." He paused, then laughed. "It's probably turned to water by now, but it'll still work."

Chiaki fetched the jar of oil, and returned to find Tooru sitting at one end of the couch, his laptop propped on top of his stomach. 

"Aren't you warm?" Tooru murmured, without raising his eyes. "Go on, take them off, I don't mind."

Normally, Chiaki wouldn't hesitate, but while it did feel a little silly to be fully dressed while Tooru was almost naked, he couldn't deny that this felt different to normal. Still, he _was_ too hot, and it would just look weird if he kept them on now that Tooru had expressly called him out on it. He quickly shuffled out of his t-shirt and shorts, and took a seat at the other end of the couch. He sat with his back to the arm of the couch, facing Tooru, and after a minute Tooru put aside his laptop and nudged his feet into Chiaki's lap. 

"You're a good boy, Chiakkun," Tooru teased, smirking at him as Chiaki wrapped his fingers around Tooru's left foot. 

Chiaki shrugged. "I promised nii-san I'd take care of you," he said, starting to massage Tooru's foot with both hands. He dug his thumbs into the arch, and moved them along the muscle of Tooru's sole.

"Ahhh, Chiakkun," Tooru sighed, sinking a little lower in his seat, his face relaxing. "That's good." He dug his heel into Chiaki's thigh and sighed again. "Can I keep you?"

"Maybe," Chiaki said, laughing under his breath. "I dunno if nii-san would approve." 

"He would if I asked him," Tooru said smugly.

A smile tugged at the corner of Chiaki's mouth. He'd rarely spent time one on one with Tooru, and it was easy to see how Hajime found him so infuriating. It was equally easy to to get hooked by his charms, however, particularly when he was like this; quiet, his usual barriers lowered. Chiaki shook his head, trying to dispel the muddle of thoughts and feelings, and made himself focus on his task. He smoothed his thumbs over the slim bones of Tooru's ankle, moving carefully over the bumps and grooves of the joint. 

"Ohh," Tooru murmured, his eyes falling shut. "You're so gentle."

Chiaki swallowed. "Is it okay?"

Tooru nodded his head against the pillow. He looked more relaxed than Chiaki had seen him all week, his chest rising and falling slowly, and his hand resting lightly on top of his stomach. The only sign that he was still awake was the faint crease between his eyebrows, that would occasionally deepen as Chiaki found a tender spot with his thumbs. 

After a few minutes, Chiaki released Tooru's foot and started to massage the other one. Tooru sighed again happily and flexed his toes against Chiaki's upper thigh. His sweet, grassy scent was stronger than usual, and muddled wonderfully with the creamy smell of the coconut oil. Chiaki gritted his teeth, and wondered how long he could hold his breath for without Tooru noticing. As if it wasn't bad enough that Tooru was almost naked, he had to smell like _that_. Chiaki realised to his horror that he was starting to get aroused, which wasn't helped by Tooru's foot nudging against his inner thigh, warm and slippery with oil. 

"Uh—" Chiaki said, his hands slowly coming to a stop.

Tooru groaned and arched his back, grinding his heel against Chiaki's palm. "Don't stop," he pleaded. "A little more."

"...Okay," Chiaki murmured, his face hot. He kept going, working his hands up Tooru's calf and trying to will away his boner. 

"There," Tooru sighed, as Chiaki's fingers reached the crook of his knee. 

Chiaki frowned. "Has your knee been bothering you?"

Tooru grunted softly. "It's just the extra weight. I'll rest it tomorrow." 

"Where does it hurt most?"

"Mm...here," Tooru murmured, reaching down to indicate. His fingertips brushed Chiaki's hands, making him shiver slightly. As Chiaki started to massage where he'd pointed, Tooru shivered. "You're good with your hands." 

The timbre of Tooru's voice was low and soft, like someone brushing their thumb over the strings of a cello. It was almost unbearably intimate, and in the close heat of the apartment, it made unwanted desire ripple down Chiaki's spine. Tooru seemed oblivious to the effect he was having; if he knew, he certainly wouldn't have wanted Chiaki's hands on him like this, no matter how good it felt, and he certainly wouldn't be arching his back and making those soft, longing noises deep in the base of his throat. 

Chiaki's face was on fire. He closed his eyes and tried to tune out the feel of Oikawa's slender limb beneath his fingers, or the flex of his toes on Chiaki's thigh. The trouble was, closing his eyes only meant he was more receptive to the other stuff; the soft little groans and sighs Tooru was making in response to his touch, and of course, his scent, thick and rich and sweet. Chiaki had never smelled it so sweet, except once, he realised, when he was younger. Tooru and Hajime had been babysitting him, and Chiaki was supposed to be asleep, but he'd crept back downstairs after Hajime had tucked him into bed, and then stood frozen, peering through a crack in the door as he watched them kissing on the couch. It had made his tummy feel funny to watch them, captivated by the way Tooru sighed and moaned while Hajime kissed his neck, and moved his hand inside the front of Tooru's shorts. He'd smelled the same way then, his scent sweet and rich; the sense memory of it hit Chiaki like a punch in the gut.

"What's that face for?" Tooru asked softly, interrupting his sudden rush of nostalgia.

Chiaki jerked his gaze up to Tooru's face, ears and cheeks pinking. Tooru was watching him with a faint smile on his face. "Eh—huh?" he yelped.

Tooru's smile widened. "What were you thinking about?"

Chiaki's flush deepened. "Nothing."

"Come on," Tooru teased, nudging his thigh again. "Tell me."

Chiaki huffed and rolled his eyes. "Are you like this with nii-san?"

Tooru grinned. "With Iwa-chan I'm _much_ worse."

"That doesn't surprise me," Chiaki mumbled. He sighed. "I dunno, I was just—thinking about how nice you smell."

"Oh!" Tooru's eyes widened. "Do I?"

Chiaki nodded. "I've always liked your scent," he admitted, not daring to meet Tooru's gaze. "Is that weird?"

"Of course not!" Tooru said, shaking his head. "I like yours too. You kind of remind me of Hajime, only you smell a bit different. Sweeter?"

Chiaki bit his lip. Back in school, around the time he'd hit puberty and gotten his first rut, other alphas had teased him about smelling too much like an omega. He'd started carrying one of Hajime's t-shirts in his school bag for a while, trying to cover up his own scent with Hajime's stronger, more mature scent. It didn't really work, but it didn't do any harm either, until the day one of the bigger alphas in his class kicked over Chiaki's bag and the t-shirt fell out. He didn't live that one down for a while. 

"What is it?"

"Nothing," Chiaki said, shaking his head. "I—I'm gonna—bathroom," he muttered, carefully pushing Tooru's foot aside. 

"Alright," Tooru said, his curious gaze following Chiaki out of the room.


	2. Chapter 2

Hajime had been gone five days when Tooru's mood started to turn. The air conditioning had finally been fixed the previous day, but Tooru was tense and irritable at breakfast nonetheless, snapping at Chiaki and then apologising immediately. 

"Are you okay?" Chiaki asked a little later, giving him a worried glance. Hajime had warned him specifically that Tooru's mood usually plummeted when he got sick, but had assured him that he probably wouldn't have to deal with that. Chiaki really hoped that he was right. The last thing he wanted was for Tooru to be unwell on his watch. "Do you need anything?" he asked, hovering by Tooru's seat at the living room table.

Tooru gave him a grim smile. "No, I'll be alright."

"If you're sure," Chiaki said, still unwilling to leave him by himself. "I could pick something up on my way home from the gym." 

"You're a sweetheart," Tooru said, shaking his head. He pushed himself up from the table with a sigh. "Really, I'm fine, just a little tired."

Chiaki reached down to help him up. "Why don't you take a nap," he suggested as he helped Tooru to his feet. "I'm sure you'll feel better."

Tooru nodded. "Mm...maybe." He sighed, and leaned heavily on Chiaki's arm. "I've been finding it hard to sleep without Hajime."

"Oh…" Chiaki said, frowning. "Well...maybe I could...uh…" He trailed off, realising he had no idea how to finish that suggestion, and beginning to regret that he'd even opened his mouth. His face began to heat. "Never mind."

But Tooru straightened up and looked at him, brown eyes wide. "Would you really?"

Chiaki shifted uncomfortably. "Um, I guess...if you want. If you think nii-san wouldn't mind."

"Oh, Hajime won't care," Tooru said, waving his hand. He gave Chiaki's arm a tug. "Come on."

"Uh—"

Chiaki didn't resist as Tooru dragged him through the apartment to the room he shared with Hajime. It usually smelled strongly of them both, but today Tooru's scent was overpowering everything else. He'd made a pile of Hajime's clothes on the bed, and Chiaki hesitated in the doorway, pulling back slightly as Tooru's grasp slid down to his wrist. 

"Are you—have you been nesting?" he asked haltingly.

Tooru shrugged, avoiding his gaze as he replied. "I suppose I was missing Hajime," he murmured. "Hang on a moment, I'll move it."

"Wait—" Chiaki began, but Tooru was already clambering onto the bed and bulldozing the pile of clothes onto the floor. As they fell, Chiaki thought he spotted a couple of his own t-shirts, but he didn't have a chance to investigate before Tooru was flopping back against the head of the bed and patting the space beside him. 

"You don't have to stay," Tooru said, meeting his eyes and then glancing away again. "But...could you just hold me until I fall asleep?"

Chiaki swallowed thickly. He'd avoided getting too close to Tooru over the past few days, at least as much as was possible while living in such close quarters. A little part of him began to spiral into panic at the thought of snuggling up to his brother's husband, while another, significant part of him was already buzzing at the thought of putting his arms around Tooru's soft middle, of breathing in the thick, sweet scent of his skin. 

"Of course," Chiaki said, trying to push down the conviction that he was a terrible person, and an even worse brother. Hajime _might_ be fine with him cuddling Tooru to help him sleep, but Chiaki would bet that his brother wouldn't be so understanding if he knew some of the thoughts that had been going through Chiaki's head over the past few days. He took a deep breath and then moved over to the bed. 

Tooru watched him for a moment, then he shuffled down and turned onto his side, facing away from Chiaki. 

It was easier without Tooru's gaze on him. Chiaki swallowed down the worst of his nerves and scrambled onto the bed, moving over to lie beside Tooru. He mirrored the other man's pose, but although he left a few centimetres between them, he could already feel the heat of Tooru's body radiating out. 

"You can get closer than that," Tooru murmured. 

It was easier said than done. Chiaki _could_ get closer, but he couldn't fight the certainty that he _shouldn't_. 

After a few moments of Chiaki's indecision, Tooru made the decision for him, reaching behind himself to grab Chiaki's hand and tug it around his waist. He pressed Chiaki's hand against his chest, his long fingers curled around it, and heaved a deep sigh. 

"Relax, Chiakkun," he murmured.

Chiaki closed his eyes and took a deep breath, letting it out again slowly. Tooru had bathed the previous evening, but all the same, his scent was as thick and cloying as it had been when they were stranded without air conditioning. The most sensible thing for Chiaki to do was to move away, but instead he pressed closer, fitting his body against Tooru's and settling his arm comfortably against Tooru's waist.

"Thank you," Tooru whispered.

"Mm," Chiaki hummed, not trusting himself to come out with actual words. He was too busy trying not to let himself get lost in the warmth and familiar, soothing scent of Tooru's skin. Not to mention desperately willing himself not to react to the closeness and the heavy scent, although it was a battle he was losing. He fervently hoped that Tooru wouldn't notice the slight swelling in the front of his shorts, but luckily enough, it sounded as though Tooru's breathing had already slowed to indicate he'd fallen asleep. Chiaki relaxed against the pillow, and closed his eyes. 

When he woke a short while later, they lay in the same position as before, except that Chiaki's nose was pressed into the short, ticklish hairs at the back of Tooru's neck, and he'd closed the slim gap he'd left between his groin and Tooru's backside. He blinked awake slowly, confused by his surroundings for a few moments. Tooru still seemed to be asleep, and Chiaki wasn't sure if he ought to extricate himself and risk waking him, or stay put. He didn't really want to leave, but he also couldn't help feeling like he was betraying his brother by being in his bed. 

Before he could make up his mind about what to do, Tooru shifted and made a soft noise in his throat. Chiaki had a momentary flash of relief, but it quickly became clear that Tooru hadn't woken up at all, and was instead shifting unconsciously, perhaps in the midst of a dream. He was also keening low in his throat: soft, longing sounds that Chiaki had never heard him make before. When Chiaki made a careful attempt at pulling his arm free, Tooru grabbed onto it more tightly. Tooru's skin was hot, almost feverish, and he sighed and pressed back harder against Chiaki. 

Chiaki huffed out softly. He wished Hajime were there, because he always knew what to do, but Hajime had left _him_ in charge.

After laying there for a couple of minutes of indecision, Tooru finally moved and released his arm, and Chiaki took the opportunity to escape, rolling away from him carefully. Once he was free, he went to check the air conditioning, but the apartment was still cool, so instead he went to the bathroom and soaked a towel in some cold water.

Tooru finally stirred when Chiaki crouched beside his bed and laid a gentle hand on his shoulder. 

"Chiakkun," he murmured, lifting his head a little, and blinking up at him dazedly. "So hot."

"I brought you this," Chiaki said, reaching out to dab the wet towel against the side of Tooru's face. Tooru moaned softly and put his hand over Chiaki's, pressing the towel more firmly against his face and neck. The sound of his voice shivered down Chiaki's spine. "Are you okay?" he asked.

Tooru sighed, then opened his eyes again and grimaced. "Feels like my heat."

Chiaki reeled backward, yanking his hand out of Tooru's loose grasp. "Your heat? But—how—"

"It can't be that," Tooru said in a weary voice, rolling over onto his back. He sighed up at the ceiling, and pressed the wet towel against his other cheek. "Although I did read that some omegas get a kind of pseudo-heat in late stages. I'll call the midwife." 

"Here," Chiaki murmured, reaching to hand Tooru his phone from the nightstand. "Do you need anything?"

Tooru licked his bottom lip. "Maybe a glass of water, if you would."

Nodding, Chiaki jumped to his feet and made his way through to the kitchen. He was grateful to have a few moments to himself; he couldn't deny that he was worried, and he was torn between the urge to call Hajime for help, and a reluctance to worry him if it turned out to be nothing. A little part of him was determined to prove that he could be relied on, and he reasoned that it couldn't hurt to wait for Tooru to finish his phone call before deciding what to do. Chiaki tried to take his time about fetching Tooru his water, but he could still hear the low murmur of Tooru's voice when he reached the bedroom again.

"—yes, I do," Tooru was saying. There was a pause, then a rustle of clothing. "Yeah, pretty wet….more than usual, yes."

Heat rushed to Chiaki's face, but Tooru wasn't finished

"No, my brother in law is here. His scent is driving me crazy. All I can think about is—"

Despite himself, Chiaki leaned forward to hear the conclusion of that sentence, but just at that moment, the floor creaked under his feet, and Tooru broke off suddenly. Chiaki grimaced, his flush deepening. He didn't know whether to make his presence known or creep back to the kitchen, so in his momentary panic, he settled for staying put.

"So you're certain that's what it is?" Tooru continued after a minute. "Yes, I will do. Thank you. Yes, see you next week. Bye."

A few moments passed, but before Chiaki could make his escape, Tooru called out to him.

"Ah—h-hey, Tooru," Chiaki said in a sheepish voice, peeking his head around the doorframe. Tooru had propped himself up against his pillows, and he was currently sitting with one hand resting on top of his stomach, while the other held the wet towel against the side of his neck. Chiaki stepped fully into the doorway, clutching the glass of water. "Um...what did they say?"

Tooru shook his head a little, and gave Chiaki a rueful smile. "Apparently I was right, it's not unusual to have a kind of...pseudo-heat." He sighed and lifted his hand to brush his hair back from his face. "I don't know why they call it that, really. Apparently the symptoms are just the same as a regular heat, except that I obviously can't get pregnant." 

"So...should I—do you want me to go?" Chiaki asked, hovering in the doorway.

"No, no," Tooru murmured, and beckoned Chiaki closer. He smiled. "I still need that drink, for a start."

Chiaki hurried over to present it to him, and Tooru drank it gratefully, downing half the glass in one go. It was easier now to see the effects of heat on him; he looked much like he had when the air conditioning went out days earlier, his limbs heavy and his hair sticking to his temples and the back of his neck. A trickle of sweat ran down from his hairline, disappearing into the back of his shirt. His scent was mouthwatering. Chiaki licked his lips and swallowed thickly. 

"Can I do anything?" he asked. 

Tooru shook his head. "Just—stay with me, Chiakkun?" He patted the empty space beside him. "Please?"

"Of course I will," Chiaki said quickly. Even if Tooru _was_ going into heat, it wasn't as though Chiaki had much direct experience of that. He wasn't Tooru's alpha, much as his instincts were starting to clamour in his chest, urging him to claim, to breed; everything he knew about caring for someone in heat had been gained from textbooks or pornography, and neither would be very useful to him here. He pushed down the faint, buzzy feelings in his chest and rejoined Tooru on the bed. Whatever was going on, Tooru needed his help, not for him to turn into a horny, drooling disaster. 

As Chiaki propped himself against a pillow, Tooru handed him the towel, and reached over to grab his phone again from the nightstand. "I should text Hajime," he murmured. He gave Chiaki a significant look. "Would you mind holding that for me?"

Chiaki blinked down at the towel. "Uh...no?"

The corner of Tooru's mouth twitched. "Here, Chiakkun," he murmured, tapping the side of his neck.

"O-oh, right," Chiaki said, his ears heating. He refolded the towel so the coolest side was on the outside, and pressed it against Tooru's flushed skin, eliciting a sigh from the other man. Sitting this close, it was impossible to ignore Tooru's inviting, grassy scent. It reminded Chiaki of countless childhood summers: of playing in the park, and eating dripping slices of ripe watermelon on the back porch, and the sound of Tooru's voice when Chiaki snuck downstairs, breaking into shards of pleasure. He shook his head to try and clear the thought, but it was too late, his cock hardening in his shorts as his own hormones surged in response to Tooru's. 

"Chiakkun," Tooru whispered. He turned partly toward Chiaki, brushing aside his hand holding the towel, and instead pushed his face into the curve of Chiaki's neck. Tooru breathed in deeply, and then sighed out again, hot breath pushing over Chiaki's collarbone. 

Chiaki was too stunned to move. And then Tooru slid an arm around his waist and pressed closer, nuzzling against Chiaki's scent gland with his nose. "T-Tooru," Chiaki said, his voice coming out embarrassingly high. His hands hovered awkwardly a few centimetres above Tooru's back. He longed to gather him closer, but all he could think of was how Hajime was going to look at him when he found out what Chiaki had done. "I-I should go."

"Stay," Tooru insisted, slipping his hand inside Chiaki's shirt and pressing it flat against his ribs. His lips were warm and soft against Chiaki's neck, pressing just below the sensitive skin of the scent gland beneath his ear. Chiaki let one of his hands fall to Tooru's shoulder and turned his head a little, pushing his nose into Tooru's soft, sweet-smelling hair. He breathed in, sliding his hand to cup the back of Tooru's neck.

"Tooru," he sighed, a shudder starting between his shoulder blades and rippling down. 

Tooru's hand whispered over his skin. "I know you want me," he whispered, moving his mouth to the curve of Chiaki's jaw. 

Chiaki swallowed. There was no way to answer that without either lying or incriminating himself. He moved his mouth uselessly a couple of times. "You're—I—"

"Chiakkun," Tooru groaned, tugging him closer. 

Panic gripped him, and Chiaki pushed himself away from Tooru. He stumbled trying to get up from the bed, crashing onto the floor instead.

"Chiaki!" 

"Ow," Chiaki groaned, more stunned than bruised. 

Tooru leaned over the edge of the bed to peer at him. "Are you alright?"

Chiaki nodded. "I—I gotta—uh." He scrambled to his feet and out of the bedroom. He was breathing hard, and his throat felt cold without Tooru's warm breath against it. Needing to escape, Chiaki went out into the hallway, wincing at the cold concrete floor under his bare feet. His hands were shaking. He pressed his back against the wall and took a few slow, calming breaths. Hajime was going to kill him. Chiaki had almost—

Swearing under his breath, Chiaki fumbled his phone out of his pocket and dialled Hajime. 

"Hey, kiddo," Hajime said cheerfully. "Everything alright?"

"Nii-san—I need to tell you something," Chiaki said in a rush. 

"Are you okay?" Hajime asked, urgency creeping into his tone. "Did something happen to Tooru?"

"No, no," Chiaki said quickly. "He's fine. We're both fine, it's just—just, some things happened, and I'm so sorry, I didn't mean—it wasn't supposed to go this far, or anywhere, I just—"

"Woah, woah," Hajime said. "Slow down, kiddo. What's wrong?"

Chiaki closed his eyes and took a deep breath. "Tooru, he started to—I thought maybe he was getting sick, but then he—and the two of us—I didn't mean for anything to happen, I promise."

There was a pause on the other end. Chiaki's stomach clenched horribly; in the moments before Hajime spoke again, a hundred terrible scenarios flashed through his mind. When Hajime did finally speak, his voice was slow and careful, a little wary. 

"What happened, Chiaki?"

"Tooru's—he's got his heat, I think? He asked me to lie down with him, and I did, and we—I mean, nothing _happened_ , but it's wrong, he's not mine, and I—I wanted to do more, I'm so sorry, nii-san, I—"

Hajime sighed. "Chiaki, calm down. How can he be in heat? He's pregnant."

"I don't know," Chiaki muttered, wincing. "Apparently it can happen. He said it's not a real heat, but it feels like it." Chiaki's face flushed. "A-and, it—it smells like one."

"Oh boy," Hajime said, heaving another sigh. He was quiet for several moments, but Chiaki didn't dare speak. He was certain that Hajime would hate him for this, for being there when Hajime should have been. And then there was the way he'd gotten so close to Tooru in such a vulnerable time, the way he'd wanted to get even closer— "I'm sorry, kiddo," Hajime said at last. "You shouldn't have to deal with this."

Chiaki opened and closed his mouth stupidly, unable to make Hajime's words match what he'd expected to hear. "Um...you're not mad?"

"Of course not," Hajime said, sounding surprised. "Trust Oikawa to do something like this."

"It's not his fault," Chiaki said quickly. "I'm the one who—who can't can't control myself."

There was another pause. And then Hajime's voice, dangerously soft. "Did something happen between you two?"

"No!" Chiaki said, heart hammering. "Nothing like that, I promise. I—I just—Tooru wanted me to lie down with him, a-and hold him, and I did. And I wanted to do more. He—he asked me to—" Here Chiaki's words failed him. His voice dropped to a faint whisper. "To...be with him."

Hajime made a low, thoughtful sound. "He asked you that?"

"But I wouldn't," Chiaki insisted. "I would never do that, you're my brother."

"Would you want to?"

"Of course not," Chiaki said, although his voice sounded unconvincing to his own ears. 

Hajime's silence dragged out for interminable seconds this time. Chiaki was aware of a door opening and closing in the hallway outside the apartment, and the faint sounds of Tooru shifting on the bed in the other room. "You know," Hajime said at last, his voice low and dangerous. "If it was anyone else, I'd drive up there tonight and tear their throat out."

Chiaki swallowed. 

"—but I trust you to take care of him." 

"Okay," Chiaki whispered. He could do this. He could withstand Tooru's demands for attention.

"So as long as you're okay with it, you have my permission to help Tooru through his heat." Hajime laughed. "I mean, not that you really need it. It's up to him, I guess. But I get it. He's always had a soft spot for you. I just want to know he's looked after."

Chiaki's heart was still slamming in his chest, his stomach still twisting. It took several moments for Hajime's meaning to penetrate. "Uh…what did you mean by 'help him'?" he asked faintly, not quite daring to believe what he'd heard. 

"You know," Hajime muttered, clearly uncomfortable. "Whatever he wants."

When Chiaki sat dumbfounded, Hajime eventually continued. 

"You—you've had sex before, right?" 

"No?" Chiaki squeaked. 

"Oh." Hajime's silence pressed down on him, but Chiaki didn't think he would have been able to speak even if he could think of something to say. "Well, uh…don't let him push you into anything, but—I meant what I said before. I trust you."

Chaiki's throat was tight. "Nii-san," he murmured.

"I mean it. You're the only person I'd trust with this." 

"Alright," Chiaki said, bewildered. "Uh, thank you?"

Hajime laughed. "God, I never thought we'd be having this conversation."

Chiaki winced. "I'm sorry."

"You don't need to apologise to me, kiddo," Hajime said gently. "If you don't wanna—" He broke off, sighing in frustration. "Your first time doesn't have to be with him. He'll be okay, he's gotten through heat on his own plenty of times."

Chiaki was nodding even though he knew Hajime couldn't see him. His tongue felt heavy and useless in his mouth, but he forced himself to say, "I want to."

Hajime huffed. "Okay then. Make sure he drinks plenty of water, he tends to forget."

"Okay."

"And—" Hajime hesitated. "You should put some towels under the sheet, it'll probably get messy."

The barrage of images those words provided made Chiaki's brain short circuit. "O-okay," he stammered. 

Hajime chuckled. "Sorry. It seems weird to wish you good luck, but uh—have...fun?"

"Oh my god," Chiaki groaned, covering his face with his free hand.

"Yeah, I'm gonna hang up now."

"Okay."

The phone beeped to signal that Hajime had ended the call. Chiaki slipped the phone back into his pocket, then slid down the wall until his backside hit the floor. He wrapped his arms around his knees, dropping his head down between them, and took deep breaths in the hot, tight space between his thighs and elbows to calm himself. 

 

—

 

Chiaki's hands were still trembling when he made his way back down the hallway to the door to Tooru's bedroom a few minutes later. 

Tooru was sitting on the edge of the bed. He glanced over at the door as Chiaki slid it open the rest of the way.

"Chiakkun," he said, his voice tight. There was a rather attractive flush across his cheeks, and a few strands of hair were sticking to his forehead. "I'm sorry about before," he said, offering a weak smile. 

Chiaki shook his head, still hovering in the doorway. "I don't mind."

One corner of Tooru's mouth twitched, and he let out a huff of laughter. "You say that a lot," he said, tilting his head to one side. "What do you really want?"

"Nii-san said I should—help you," Chiaki said haltingly. "With your heat."

Tooru's eyebrow twitched. "So that's what he was talking about. He just texted me, but I couldn't make sense of it." He sighed and tossed his hair, shaking it out of his eyes. "Do you _want_ to help me?"

Chiaki's mouth was dry. He ran his tongue over his bottom lip. "Do you mean—we'd, uh—have sex?"

It was hard to tell if Tooru was blushing too, or if it was just the effects of his oncoming heat, but Chiaki could have sworn he seemed a _little_ less self-assured than normal. "If you want to," Tooru said, lowering his gaze briefly, before searching out Chiaki's eyes again. "I'd like that very much."

"Really?" Chiaki asked, eyes widening. 

Tooru huffed, starting to smile again. "Yes, really. Has nobody ever told you how attractive you are, Chiaki-chan?" Wordlessly, Chiaki shook his head, and Tooru stretched a hand out toward him. "Come here." 

This, Chiaki realised, was his chance to change his mind. If he took a step back now, Tooru wouldn't push him. He could content himself with fetching glasses of water and cool cloths, and holding his breath when he was in Tooru's bedroom. They would probably never mention it again. 

"I don't really know what I'm doing," Chiaki murmured, taking a few steps over to the bed. He took Tooru's hand, and let Tooru pull him closer. 

"Have you kissed someone before?" Tooru asked, looking up at him. His eyes were very wide and dark. 

Chiaki's heart was pounding so hard he almost couldn't breathe, let alone speak, so he settled for nodding his head.

The corner of Tooru's mouth twitched. "Show me," he murmured. 

Chiaki nodded again. He wet his bottom lip, then lifted his trembling hands to cup Tooru's face. It felt like a transgression, despite what Hajime had said to him. Tooru wasn't his omega; he and Hajime had always belonged to each other and nobody else, but he was looking up at Chiaki now with warm, trusting eyes, his chest rising and falling sharply. Chiaki did his best to push down his discomfort, and brushed the pad of his thumb against Tooru's jaw. Tooru tipped his head back and closed his eyes, parting his lips a fraction. Chiaki's heartbeat was deafening. He lowered his head, and pressed to lips to Tooru's.

Tooru's mouth was soft, but he pushed back after a few moments, parting wider and nudging his tongue against Chiaki's bottom lip. Surprised, Chiaki opened his mouth, unresisting when Tooru stroked their tongues together, then pulled away again. 

Chiaki felt him smile, and pulled back so there was a hair of space between them. "Don't laugh," he whispered reproachfully. 

"I won't," Tooru murmured, sliding one of his hands up to Chiaki's shoulder. He grinned. "I promise."

They kissed again, slow, Chiaki the first to deepen it this time. Tooru tipped his head back after a moment and sighed as Chiaki pressed in with his tongue. Feeling braver, he stroked his fingers down the side of Tooru's neck, then broke off and kissed the corner of his mouth, then his chin, tilting Tooru's head gently to kiss his jaw, and then the side of his neck. His mouth glanced off the space below Tooru's ear, just shy of his scent gland. Under his touch, Tooru shivered.

"Don't hold back," he murmured, one of his hands clutching Chiaki's shirt.

Chiaki's breath came out shivery, but he grabbed hold of his courage and closed his lips over Tooru's scent gland, strumming it with the tip of his tongue. 

"Hah—Chiakkun," Tooru breathed, grabbing onto him more tightly. He hummed in obvious pleasure, a sound which struck Chiaki firmly in the gut. 

They broke apart briefly, both panting. Chiaki let his hands fall away from Tooru's face. "What, um—what should I do?" he asked, his cheeks flushing. "What do you normally—" His flush deepened. "It's my first time." 

"With someone in heat?" Tooru asked quietly. 

Chiaki shook his head. "With anyone."

Tooru grinned. "Usually, you take a bath together." 

Chiaki's eyes widened. "Oh," he breathed softly, struck by the thought of it. "Alright."

"Why don't you go and fill the bath," Tooru murmured, his fingers toying with the short hairs at the back of Chiaki's neck. "I'll be through in a minute." 

Somehow, Chiaki made it to the bathroom without walking into a wall, where he began to fill the bath with warm water. 

"Not too hot!" Tooru called from along the hallway. 

While he waited, Chiaki toyed with the edge of his t-shirt, unsure whether he should take off his clothes, or wait for Tooru. He finally decided on removing it, and reached back to yank it over his head. When he came up for air again, Tooru stood in the doorway, a faint smile on his face. 

"Oh, uh—"

"Tut tut," Tooru murmured, smile widening. "You didn't wait for me."

Chiaki's flush deepened, spreading down to his neck. "I—I wasn't sure what I should do."

"I'm teasing," Tooru said in a low voice, reaching out to him. He spread his hands against Chiaki's bare chest, flicking one thumb pad against his nipple. 

Chiaki blinked up at him, his heart racing. Tooru was a good eight or nine centimetres taller than him, but Chiaki had never really noticed before; Tooru had always been bigger than him, after all. Tooru's hands ran down the outside of his arms, making him shiver, so Chiaki responded by putting his hands on Tooru's hips. "Can I undress you?" he murmured.

Tooru grinned, and nodded. Swallowing down his nerves, Chiaki pushed aside the unbuttoned shirt Tooru wore, one that Chiaki suspected he'd borrowed from Hajime, and tugged it down and off his wrists. He mirrored Tooru's touch next, putting his hands on Tooru's shoulders and then running them down the outside of his arms, his touch gentle. 

"Is this okay?" he whispered.

When Tooru nodded, he kept going, tugging the stretchy tank top up and over Tooru's head, exposing his belly and the soft, thin bralette he wore. He tried to tell himself this was no different to seeing Tooru in his underwear all week, but it wasn't the same to be the one helping him shed his clothes, running reverent fingers over his skin. Arousal surged through him, making him dizzy with it; he didn't know where he wanted to touch next, let alone where Tooru might want him to touch or not. It was already a thousand times better and more intense than any fantasy he'd had.

Seeing that Chiaki had stalled with a hand on his hip, Tooru grabbed hold of it and lifted it to his chest, then pressed it against his left breast. 

"God," Chiaki groaned, cupping his hand around it. He rubbed his thumb back and forth until he found Tooru's nipple, starting to stiffen under his attentions. With a quick glance at Tooru's face to seek permission, he pushed the bralette up, then pulled that off over Tooru's head too, so that he was bare from the waist up. "You're, uh—really beautiful," he said shyly. 

Tooru beamed at him. "Flattery will get you everywhere, Chiakkun," he said approvingly, leaning down to kiss him again. As they kissed, Tooru unfastened Chiaki's shorts, and then slid his own down over his hips, and the two of them clumsily stepped out of them until they were both left in just their underwear. "Help me wash," Tooru murmured, reaching to push his underwear down and then kicking it aside without ceremony. He moved under the shower head and turned on the spray, leaving Chiaki to quickly scoop up their clothes to avoid them getting wet. 

When Chiaki finally turned to look at him, Tooru stood with his feet slightly apart, dragging a wet cloth across his chest. He looked over at Chiaki and beckoned him closer. 

Chiaki walked over to him. He wasn't embarrassed by his own nudity, or Tooru's for that matter, but he couldn't help wondering what Tooru would see when he looked at him. Chiaki knew that he didn't compare very well to his brother; he was shorter, his build slighter, and his face was rounder, more babyish. 

"Here," Tooru said in a low voice, handing Chiaki the cloth. He turned, presenting Chiaki with his back, and spoke over his shoulder. "Don't be shy."

"Mm," Chiaki hummed, unable to make a coherent sentence. He wet the cloth under the warm spray, then held it over Tooru's back and wrung it out, letting the warm water run down his spine. Tooru had stopped playing volleyball about a year earlier, and hadn't yet lost any of his physique; his shoulders were broad, his waist narrow, except for the additional weight he'd gained thanks to the baby, which really was minimal. HIs shoulders were freckled, and Chiaki couldn't help leaning in to press his mouth there, to scrape his teeth over Tooru's soft skin. The hand holding the cloth he wound around Tooru's waist, moving closer to him, holding his breath as he daringly dragged the cloth around the weight of Tooru's right breast. 

Tooru sighed, his breath coming out unsteady. "Chiakkun," he said, leaning back a little, letting some of his weight rest against Chiaki. "Touch me." 

Chiaki lifted his other hand and reached around Tooru's chest to cup his breast, squeezing it gently. His fingers brushed over Tooru's nipple, and he hesitated for only a moment before pinching it between them lightly. 

Tooru tipped his head back with a groan. "Mm—harder." 

Abandoning the cloth, Chiaki cupped Tooru's small breasts with both hands, and pressed closer to his back, so that his erection rubbed against Tooru's backside. His breath shuddered out at the sensation; he was already out of his depth, but he trusted Tooru to keep his promise and not to laugh at him, and more than that, Chiaki trusted him to be patient and teach him. Tooru had always been the best volleyball teacher when he and Takeru were kids, and Chiaki couldn't think of anyone he'd rather do this with for the first time, strange as it was. 

Tooru hummed in encouragement as Chiaki gently massaged his breasts, and squeezed his taut nipples. Chiaki couldn't help moving his hips, grinding his cock against Tooru's plump backside, and his throat caught when Tooru started to press back, hips rolling sinuously. They started to grind against one another, soft moans building, and Chiaki bit his lip suddenly when he realised that he was getting close to coming. 

He jerked his hips away from Tooru's, groaning with the effort of holding himself back, his fingers digging into the flesh of Tooru's breasts. 

"Chiakkun?" Tooru murmured, a little out of breath. 

"S-sorry," he stammered, forcing himself to let go. 

As his hands fell away, Tooru turned to face him. "Is everything alright?" he asked, reaching up to cup Chiaki's jaw. 

Chiaki nodded tightly. "It's just—a lot," he said, forcing a grin. 

Tooru cooed at him softly and ducked down to kiss him. "I'm sorry," he murmured. "I keep forgetting how intense everything is the first time." 

"No, no," Chiaki said quickly, flushing. "I mean—kinda, yeah." 

Tooru laughed quietly. "Come on," he said, putting his hands on Chiaki's shoulders and walking him back a few steps. "Let's get in the tub."

Tooru and Hajime's bath was somehow big enough to fit both of them, even with Tooru's added curves, and Chiaki gladly sacrificed himself to sit at the tap end so that Tooru could relax. He didn't do so for long, however, before moving closer to Chiaki on his knees, and kissing him again. 

"You can put your hands on me," Tooru murmured against his lips. "Don't be shy. I want you to touch me." 

Chiaki hesitated still. "What about, uh…" 

"Hajime will understand," Tooru insisted, grabbing one of Chiaki's hands and moving it to his hip. "Mm, there." 

"Tooru," Chiaki sighed, pulling him closer as he tipped his head back for another kiss. They moved against each other languidly, Chiaki moving his hands over Tooru's back, and with some slight hesitation, over his ass and the backs of his thighs. Chiaki's hips were twitching with anticipation, especially now that he'd had a hint of how it felt to press up against Tooru's naked body. He moved his hands slowly down Tooru's back again, lingering over the pert, round curve of his backside, and then ran one hand down his thigh, slowing even further, pressing his fingertips in as he dragged it back up again. He found the first hint of slickness between Tooru's legs and let out an involuntary groan, which Tooru echoed back to him. 

"Can I touch you, Chiakkun?" Tooru asked, breaking away. 

"A-are you sure?" Chiaki stammered, watching with wide eyes as Tooru's hand slid down his chest and then his stomach. "You don't need to— _ah!_ —m-make _me_ feel good." 

"I want you to enjoy it too, Chiakkun," Tooru murmured, putting a finger under his chin and tilting his face up to peck his mouth. "It wouldn't be much fun for me otherwise." He grinned as he pulled away again. "Besides, I want you to last long enough to get that pretty knot inside me. So let's take the edge off, hmm?" 

Chiaki flushed. "Um…" 

"I'm going to make you come," Tooru clarified, finally wrapping his fingers loosely around Chiaki's cock. 

"Ahh—hhh—" Chiaki groaned, his ability to speak severely hampered by the movements of Tooru's wrist. His hips jerked up instinctively, thrusting into Tooru's grip. "T-To—oru—"

Tooru grinned, leaning closer to him to kiss his unresisting mouth as he worked Chiaki's cock quickly, his touch merciless. "Let go, Chiaki-chan," he murmured, lips soft against Chiaki's cheek. 

"Tooru," Chiaki gasped, raising his hands to Tooru's waist, fingers digging into his flesh. He closed his eyes, shuddering, his breath coming in short pants. He was close already, but he was far gone enough not to care that Tooru might laugh at him about it. He thought back to what Tooru had said just a minute ago, that he wanted Chiaki to knot him, and just like that he was tipping over the edge, burying his face between Tooru's breasts as he cried out softly. 

"There now," Tooru murmured after a moment, stroking his fingers through Chiaki's wet hair. "Feel good?" 

Chiaki nodded, helpless. It took a great deal of effort to make himself let go, and lift his head. When he finally managed it, Tooru grinned down at him, and Chiaki raised his hands to draw him down into a kiss. 

"Thanks," he whispered, breathless. 

Tooru laughed under his breath. "Don't thank me yet," he said sweetly. "I've barely started with you yet." 

Chiaki groaned at the inherent promise, although all he could really think of just then was _warm, soft, more_. Even just Tooru's hand on him had been more than anything he'd experienced before. 

"Let's dry off," Tooru suggested, sitting back to rinse himself in the warm water. Chiaki's words stuck in his throat when he realised Tooru was washing his come off his hands and belly. 

Chiaki climbed out first, and reached in for Tooru, who was flushed and weak-kneed despite the tepid bath water. 

"My heat," was all he said in response to Chiaki's concerned look. 

They patted themselves down with towels, and Chiaki took the spares into the bedroom to lay them under the sheet as Hajime had suggested, blushing the whole time he worked. Tooru was standing in the doorway when he looked up, his knuckles white where he gripped the wood. 

"Are you okay?" Chiaki asked, stumbling over to help him to the bed. 

Tooru nodded. "Just a bit dizzy." He crawled onto the bed on his hands and knees and then groaned, shoulders sinking forward so he could press his face against the sheets. "Mm…it smells like you both."

"It does?" Chiaki ventured. "Is that…good?"

"It's _perfect_ ," Tooru groaned. He rolled over onto his back, gesturing for Chiaki to join him. He looked almost regal, sprawled casually amongst the pillows and bunched up covers, one knee drawn up a little way, so that Chiaki could see, faintly, the red glisten between his legs. "Are you sure you want to do this?" he asked, as Chiaki crawled up beside him. 

Chiaki nodded. "Um, are you?" 

"Dying to," Tooru said, rolling to face him. He grinned. "Where do you want to start? 

It wasn't a question that Chiaki even knew how to begin answering, but he couldn't deny that his orgasm in the bath had cleared his head a little. He let his eyes roam over Tooru's body, now that he could do so with impunity. Before he'd even really thought about it, he reached out to rest his hand against Tooru's stomach, almost at though he was seeking permission. 

"She doesn't mind either," Tooru assured him.

Chiaki blushed a little. "It makes me feel a bit like Hajime's here, looking over my shoulder." He gave a self-conscious laugh. "I know that's stupid." 

Tooru shook his head. "I know what you mean. But it's just us, Chiakkun. And besides," he added with a wicked smile. "If you're worried about what Hajime would think, better do your best to impress him." 

This was more than enough encouragement. With trembling hands, Chiaki cupped one of Tooru's swollen breasts, then brought his mouth to the large nipple. It was hard and hot against his tongue, and as he began to stroke it with his lips and tongue, Tooru shuddered beneath him and clutched at his head. 

"O—oh, good boy, Chiaki-chan," Tooru said breathlessly. His fingers raked through Chiaki's hair. "You can suck a little harder than that if you want to."

Chiaki did as he suggested, and was rewarded with the sound of Oikawa's voice melting into a delicious moan. His scent grew thicker and heavier, laying siege to Chiaki's senses. Heat began to roll up from his chest, flushing his neck and then his face. "Tooru," Chiaki sighed, pressing closer, slipping his arm around Tooru's waist. 

"Careful," Tooru moaned after a minute, his fingers gripping tightly where they were still tangled in Chiaki's hair. "It, ah—mm, Chiakkun—"

Chiaki kept sucking, and then blinked, startled, when a thin, sweet fluid suddenly filled his mouth. He swallowed it down without thinking, then lifted his head, and pinched Tooru's nipple between thumb and forefinger instead. More of the thin fluid trickled out, running over his fingers. "Woah," he murmured. 

"Oh," Tooru sighed, his mouth twitching. "I should've warned you, my milk started coming in a couple of weeks ago."

"Fuck," Chiaki groaned, squeezing a little tighter. "That's so hot."

"You really think so?" Tooru asked, his smile broadening. 

Chiaki nodded, and lowered his head to taste again. There was something intensely soothing about it, suckling Tooru's fat nipple and feeling the sweet liquid coating his tongue. As he nursed, Tooru lifted his knee and rocked down against Chiaki's thigh, encouraging him to push his leg between Tooru's. Chiaki did so, his stomach curling at the warmth of Tooru's thighs, and the wet heat of him as he started to grind down against Chiaki's leg. 

"Ohh, Chiakkun," Tooru sighed, shifting a little in place. He pushed his fingers through Chiaki's hair again, tugging it almost painfully. "Mm...Chiakkun." He gave another sharp tug, and Chiaki lifted his head, tip of his tongue poking out to catch a stray trickle of milk on his chin. "Want to touch me?"

"Mm," Chiaki hummed, nodding eagerly. 

Tooru rolled onto his back, shoving a pillow under his shoulders to prop himself up, and reached for Chiaki's hand. "Have you touched an omega before?" he murmured, sliding Chiaki's fingers over his stomach, then his hip. "Down here?"

Chiaki swallowed thickly. "N-no. I mean, uh—only—only through clothes, not—" He trailed off into a low whine when his fingers brushed over Tooru's coarse, damp pubic hairs, and then plunged deeper to the hot, slippery centre of him. 

"Start gently," Tooru whispered, guiding Chiaki's fingers lower, pushing them into the soft, spongy wet folds, then back again, showing him where to circle his fingers. "Touch my clit."

"That's it?" Chiaki murmured, circling it with his fingertips, sliding easily over it. "Does it feel good?"

Tooru nodded, and then he took Chiaki's hand again and slid it further back, lifting one of his legs to open himself wider. "And here's where you're going to fuck me," he said, low against Chiaki's ear. If Chiaki hadn't just come, there was a very real chance that would have tipped him over the edge. And then Tooru pushed, and Chiaki's middle and ring finger plunged into the soft puddle of liquid heat between his legs.

"O-oh," Chiaki moaned, burying his face against Tooru's shoulder, pressing his fingers deeper. It was a thousand times greater than he'd imagined, so wet and warm. He pulled back and thrust in again, repeating it a few times, then nosing against Tooru's jaw to ask for reassurance. 

"It's good, Chiaki-chan," Tooru murmured, stroking gentle fingers through his hair. "Don't stop."

Chiaki kissed Tooru's throat, then nuzzled around until he found Tooru's scent gland again, and started to suck it as he circled around his clit once more, spreading around the slippery fluid, and smiling when he felt Tooru shiver under his caress. He couldn't help thinking of Tooru's words from before; he wanted to make Tooru happy, but he also wanted to make Hajime proud, to do right by his omega. 

"Chiakkun," Tooru sighed, rolling his hips to press down against Chiaki's hand. He turned his head and caught Chiaki in a kiss, biting down on his bottom lip and rolling it between his teeth, in a way that sent a shock of arousal down Chaiki's spine. "Mm...why don't we put that lovely mouth of yours to better use?" Tooru suggested, stroking his thumb over Chiaki's lips. He waited for a moment, until Chiaki's eyes widened in realisation. "Want to try?"

Chiaki couldn't agree fast enough, his words of assent stumbling over each other. 

"It might be hard to reach like this," Tooru fretted, looking down at the significant swell of his stomach. 

"I'll manage!" Chiaki said, his enthusiasm not dampened one iota. "You'll have to tell me what to do though."

Tooru's mischievous smile returned. "You're a good kisser, Chiakkun," he said in a low voice. "Pretend it's like kissing, but more tongue and less teeth."

Chiaki nodded. "Okay." He hadn't stopped moving his fingers between Tooru's legs, but he withdrew now, to a soft sigh from the other man, and awkwardly shimmied down the bed. It wasn't his first time seeing an omega's pussy; he was an adult, he'd looked at porn before, but it was his first time seeing one up close. He could see now Tooru's clit, poking up: dusky pink and shiny slick, and frilling down from it, the thick, soft-looking lips of his vulva. 

"Like what you see?" Tooru teased. 

"It's _beautiful_ ," Chiaki breathed, meaning it. 

Tooru laughed, breasts and belly jiggling, and Chiaki groaned again.

"Okay," he said, half to himself. He moved closer, wrapping his arm around Tooru's raised leg, and then kissing the soft, damp skin of his inner thigh. A wet patch had already formed on the sheet beneath him, and as Chiaki watched, a fresh pulse of thick, creamy fluid poured out of him. Instinctively, Chiaki leaned in for a taste. 

It was a little bitter, saltier than he'd expected, and he licked his lips thoughtfully as the taste dissolved on the back of his tongue. And then he leaned in again and stroked his tongue up the length of Tooru's folds, ending with a kiss when he reached his clit. He repeated this a couple of times, and then he recalled what Tooru had said about kissing, and he started trying to apply that instead, alternately sucking on the soft, blood-hot lips, and tracing his tongue around the edge of Tooru's hole. He was rock hard again, thinking about what it would be like to hold his cock there, to rub against the slick folds, to push into that wonderful, slick channel. Tooru was quietly encouraging, offering him low-voiced praise, and soft, high whines of pleasure. Chiaki closed his eyes and ground his cock down against the mattress, trying to focus on the task at hand.

"Chiakkun," Tooru groaned after a few minutes, his voice tight. He spread his legs wider. "My clit, suck on it, please—"

Chiaki hurried to obey, drawing the hot, throbbing flesh into his mouth and flicking it with his tongue, before starting to suck on it. Tooru positively _wailed_ in response, his hips rolling up to chase the sensation. 

"F-fuck me," Tooru gasped. "Your fingers—anything—don't stop—!"

It was difficult to thrust his fingers in and out of Tooru's pussy at the same time as suckling determinedly at his clit, but he did his best to manage the two, and was rewarded after a minute or two by the sensation of Tooru suddenly tensing, and then a heavy rush of slick that soaked his hand to the wrist, Tooru's cunt clenching down tight around his fingers. Unsure how long he was supposed to keep going for, Chiaki kept pumping his fingers slowly, sucking gently. Just as he was about to give up, his hand and face aching, Tooru suddenly convulsed and came again, crying out loudly this time. Chiaki stared up at him in shock, his wet mouth hanging open and his hand frozen with his fingers halfway in, until Tooru finally groaned and nudged him away. 

"Chiakkun," he sighed, hands grasping at Chiaki's shoulders. 

Clumsily, Chiaki climbed back up, and was treated to the shockingly erotic sensation of Tooru's tongue thrust deep into his mouth, swallowing a moan when Tooru tasted himself on Chiaki's mouth. 

"Chiakkun," Tooru gasped when they parted, clutching his face between both hands. "That was—that was—" He sighed, grinning, and pressed their foreheads together. "It was perfect." 

"Really?" Chiaki asked, beaming.

Tooru nodded. "Now fuck me, please, before I lose my _mind_."

Chiaki's stomach swooped. "O-okay."

It took a little more careful arrangement, but finally they managed to find a comfortable position with Tooru on his side, a cushion wedged under his bump, while Chiaki spooned him. Despite his words, Tooru didn't seem to be in any hurry, or perhaps he was enjoying the feel of pressing his hips back while Chiaki's cock slipped uselessly against the backs of his thighs and glanced off the slippery mouth of his cunt. Chiaki tightened his arm around Tooru's middle and adjusted his hips to try another angle; for a moment, there was pressure and heat against his cock, and then it slipped away again, squishing up against the wet lips of Tooru's pussy. To his horror, Tooru started giggling.

"Fuck," Chiaki groaned, pressing his flushed face against Tooru's back. "S-sorry, I really don't know what I'm doing."

"No, no, don't be silly," Tooru soothed, twisting to look over his shoulder at him. "Anticipation is half the fun, you know," he said, winking when Chiaki finally lifted his pink face again. "But I'll stop teasing you."

Chiaki grimaced. "Thank you," he said, although he barely finished the words, distracted by Tooru reaching down between them to grasp Chiaki's cock between his fingers. He angled it again, tilting his own hips to accommodate, and this time Chiaki felt the heat and slickness, and then a spine-tingling pressure as the head of his cock suddenly slipped inside. "Oh," he groaned, pressing his face against Tooru's back again, fingers creeping up to curl around his breast. "Oh, oh _fuck_."

Tooru groaned in response. "That's it, Chiaki-chan," he said, his voice soft with relief. "God, that's it."

Chiaki pressed in the rest of the way, slowly, gritting his teeth to keep from knotting immediately, which would have been impossible if Tooru hadn't already brought him off. He panted with the effort of holding himself back, fingers squeezing reflexively around Tooru's breast, barely noticing the thin milk spilling over his fingers. Sweat was starting to stick their bodies together, and Chiaki's fingers were sticky against Tooru's chest, but none of that seemed important beside the thrilling, electric feeling of being inside him: the tight clench around his cock, and the easy, instinctive slide, in and out. It took him a minute or so to find his rhythm, but Tooru helped, rocking his hips to meet Chiaki's thrusts. Both their breathing began to climb, and Chiaki could feet Tooru's frantic heartbeat under his fingers as they both started to move faster together.

"Chiakkun," Tooru groaned, shuddering. "Mmm, harder, please." 

Although he was wary of being too rough, Chiaki obediently picked up the pace a little, rocking forward harder, faster. "Is this okay?" 

"It's good," Tooru gasped. "Don't stop."

"I-I dunno how long I can last," Chiaki admitted, too turned on to be ashamed. 

"That's okay, don't worry about that," Tooru insisted, grabbing Chiaki's hand and linking their fingers together. "I want your knot."

That alone almost pushed Chiaki over the brink, but he managed to last for a few more shuddery strokes before he was coming, the feeling more intense than anything he'd experienced, and that was before he felt the unfamiliar sensation at the base of his cock that was his knot swelling to tie them together. It was a little unsettling, but it also made the aftershocks of his orgasm more intense. 

"Chiakkun," Tooru murmured after a few moments, as Chiaki was drifting, dazed by the afterglow. 

"Mm?"

Tooru tugged at Chiaki's hand, curling their fingers together more tightly. "Thank you."

Chiaki laughed under his breath, still a little lightheaded. "I don't think I did that much."

"You did," Tooru said, pressing back against him. "This week would've been miserable without you."

"Well...you're welcome," Chiaki murmured. His eyes were starting to close, despite his best efforts. 

Tooru laughed. "Get some rest, Chiakkun," he murmured, patting Chiaki's arm. "You're going to need your strength for round two."

"Mm," Chiaki hummed, already half asleep.

**Notes for the Chapter:**

> So there might be a (hopefully shorter) third chapter in the works, but be warned that if it happens, it'll feature a threesome w Iwa, Oikawa and Chiaki, so ditch now if that's not gonna be your jam! It won't be explicitly incest but there will be mild hints of slightly inappropriate fraternal behaviour so consider yourselves warned ♥

**Author's Note:**

> [my iwaoi fic](https://twitter.com/notallbees>RT%20on%20twitter</a>%20%20%7C%20%20<a%20href=) | [my a/b/o fic](https://archiveofourown.org/works?utf8=%E2%9C%93&commit=Sort+and+Filter&work_search%5Bsort_column%5D=revised_at&work_search%5Bother_tag_names%5D=Alpha%2FBeta%2FOmega+Dynamics&work_search%5Bexcluded_tag_names%5D=&work_search%5Bcrossover%5D=&work_search%5Bcomplete%5D=&work_search%5Bwords_from%5D=&work_search%5Bwords_to%5D=&work_search%5Bdate_from%5D=&work_search%5Bdate_to%5D=&work_search%5Bquery%5D=&work_search%5Blanguage_id%5D=&fandom_id=758208&user_id=notallbees)
> 
>  
> 
> I...don't know where this came from. I blame mousecat. 
> 
> Sometimes I remember that Chiaki isn't canon, and then I am very sad. If Chiaki not being real makes you sad too, please leave a comment. Don't suffer in silence.
> 
>  
> 
>  **Warning:** This fic may be triggering for those with gender dysphoria.
> 
> So I write Alpha, Omega or Beta as the primary gender designation and Male/Female as the second. So alphas usually have dicks (in the case of female alphas, they're essentially repurposed clits). Omegas usually have vaginas/uteruses etc (honestly I just can't not think about ass babies and I refuse to have a world with ass babies) and male omegas often have large clits that are basically vestigial penises.
> 
> Ignore all of that if it makes you uncomfortable, or if you really love ass babies.


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